Morning starts sometimes affect the average fuel mileage by 4/10ths of a mpg. Which would have the least affect on fuel mileage. A. Allow the engine to idle in the garage until it is warmed up or, B. Continue to drive slowly and allow it to affect the mileage?
I vote for neither... Drive briskly at the beginning of your trip. The ICE will be on no matter what you do, but i've found you can minimize the time by accelerating more aggressively (within reason of course) to try to warm up the engine and the catalytic converter. At some point, the system will be warm enough to allow ICE shutoff, and your mileage should come back. Letting it sit in the garage to warm up doesn't really have the desired effect. It's registered (rightfully so) as a period of 0.0 MPG , and even if you wait until the Prius warms up, and then shuts off the ICE before you move the car, it still won't allow you to use the electric only mode very much or allow the ICE to shut down while the car is moving. The minute or so of the Prius warming up before it stops isn't enough for it to allow the most efficient driving.
bad advice... it is never good to drive aggresively. it is also not necessary to warm up the car if the weather is not extreme. the warm up cycle is unavoidable.
I never said drive aggressively... I meant don't try to avoid accelerating, and don't bother babying the car in the beginning. Example: I have a hill I have to go over on my daily commute to work right there in the beginning. I've found that (within the speed limit, and the traffic around me of course) if instead of simply trying to maintain my speed going up the hill, if i put an extra load on the ICE going uphill, by the time I get to the top, I can use stealth mode, I can glide, and the ICE cooperates and shuts down when it's not in use... Otherwise, the ICE stays on for longer trying to warm itself up. You can fight it, your you can go with it and try to help it warm up.
i vote for C. use EV switch until ready to maintain constant mid-30s mph then, D. go ahead and use the engine and don't baby the car. the slower you drive the less you're getting for your buck (or gallon). that's my strategy anyway.
I deplete the battery the night before by using the EV switch for the last 1/2 mile before my house when I come home, then with a depleted battery in the morning when I start off I use the engine to both warm itself up AND charge up the depleted battery. The bigger the load you can put on your engine the more efficient it is.
There is one way to avoid it get a block heater. My first bar on the consumption screen has gone from around 25 to around 50.
some time ago (maybe a year) some of the techno experts over in Japan apparently determined that the best way to warm up is actually to start the car, let it run/idle until it shuts itself down (about 1 minute with cold start). Then start. I don't recall the details and I don't know what the best way to search for that old thread would be (if it didn't get lost).
That was the new stage but it required the EV button after the 1 min of battery charging to stop the engine. Then you could drive with EV as desired during the warm up when it would otherwise be locked out. I tested it quite a lot, and found it helped sometimes and not others. So I stopped bothering. The variability was caused by the timing of the 2 traffic lights I hit during warm up.
Hey, that's what I've been doing. When the car starts, the ICE will run for a couple of mins depends on temperature. During that period, if you idle, you can see it's also charging the battery besides warming up. If you drive the car, I notice that the ICE still runing, but it's not charging the battery all the time. So I figure just capture as much energy from ICE as possible during warmup. Then drive when ICE shuts off or when it stops charging the battery.
I read somewhere that during warm up, if the ICE isn't needed to drive the car, it goes into an 'inefficient' mode (from the point of view of producing motive power, but produces a lot of heat [relatively]) to warm up quickly, unless the driver demands power that the electric motor alone cannot satisfy, in which case it reverts to a 'normal' mode (whatever that is for a Hybrid system) and helps move the car. This fits in with my observations (on my Classic Prius, at least) that if I drive away immediately on getting the READY indication, it seems to use electric only (up to 30/40 mph - my local speed limits) for the first ¼ mile or so, even if the battery gauge is at 50% (the Classic gauge only shows 25%, 50%, 75% or 100%, and possibly 0% - but rarely display anything but 50% or 75%). Normally, if it's showing 50% it tries harder to charge the HV battery, but not during this warm-up period. The ICE during this time feels almost is if it is totally separate from the Hybrid system and 'doing it's own thing'. It then quite noticeably joins in again as presumably it has reached a temperature it is prepared to live with. If I'm stationary on first switching on, it will show a flow of energy to the HV battery for about 10-20 seconds, then it seems to go into this mode, run slower and the indication of recharge flow stops.
Drive it. Idling in your garage you get zero MPG. The engine is going to run anyway right after turning the car ON to warm up the catalytic converter, so you might as well be moving and make use of it while it does so.
Thanks everyone for your input. I must conclude that this is one of those subjective answers. I must assume it is the nature of the beast. It makes sense to me to just drive the vehicle and allow it to warm up naturally.
